A 9-year-old boy is brought to the office by his parents due to knee pain.  His mother states, “His left knee has been intermittently painful and swollen for approximately 2 weeks, but it’s gotten a lot worse over the past 5 days.”  The patient plays basketball but has had no recent trauma to the knee area.  He has had no fever, headaches, or chest pain.  The patient recalls a tick bite 3 months ago during a camping trip in Pennsylvania.  He does not remember developing a rash at that time.  The patient has congenital hearing loss and wears a hearing aid.  He takes no daily medications and has no known allergies.  Temperature is 36.7 C (98 F) and blood pressure is 100/70 mm Hg.  Physical examination shows a well-appearing child with a moderately swollen, warm, and mildly tender left knee.  There is no erythema.  Minimal pain is elicited with full extension of the knee.  The patient is able to stand and bear weight.  Sensation is intact.  Capillary refill in the bilateral lower extremities is brisk.  There are no rashes or petechiae.  Laboratory results are as follows:

Arthrocentesis of the left knee is performed, and synovial fluid analysis reveals a white blood cell count of 18,000/mm³ with 85% neutrophils.

Item 1 of 2

Which of the following tests is most likely to identify the cause of this patient’s condition?

Item 2 of 2

Left knee arthrocentesis relieves the patient’s swelling, and he is now able to walk almost normally.  After 3 days, the patient returns for a follow-up visit.  His parents are concerned about his ability to participate in sports.  A mild effusion is present on left knee examination.  Laboratory results are as follows:

Which of the following is the most accurate description regarding this patient’s prognosis?

A 3-year-old girl is brought to the office for intermittent crampy abdominal pain that has been present for 4 months.  Initially, the pain was associated with episodes of loose stool.  Over the past month, the patient has had intermittent painful constipation.  For the past 3 days, she has had flatus but not stooled.  Her appetite has decreased and she has lost 1.5 kg (3.3 lb) since these episodes started.  The patient has no significant medical history other than an episode of coughing and wheezing 6 months ago while she and her family were visiting relatives in Venezuela.  Her immunizations are up to date, and she takes no medications.  Temperature is 36.7 C (98 F), pulse is 108/min, and respirations are 20/min.  On physical examination, the patient is awake but appears tired.  The mucous membranes are moist.  The lungs are clear to auscultation without wheezing or rales.  The abdomen is distended and mildly tender, with no rebound or guarding; hyperactive bowel sounds are present.  There is no hepatosplenomegaly.  Laboratory evaluation reveals the following:

Appropriate tests are performed, and the diagnosis is discussed with the family.  Which of the following is the most accurate statement regarding this patient’s prognosis?

A 17-year-old girl comes to the office for evaluation of a generalized rash.  The rash was present when she woke up this morning and does not feel painful or itchy.  For the past 10 days, the patient has had a sore throat, fever, fatigue, and body aches.  She had a bottle of amoxicillin from a recent episode of pharyngitis and took a few pills this week, but the symptoms did not resolve.  Her only medical problem was major depression, which resolved with behavioral therapy 3 years ago.  She is sexually active and takes oral contraceptive pills.  The patient takes no other medications.  She does not use tobacco, alcohol, or illicit drugs.  Temperature is 38 C (100.4 F), blood pressure is 110/76 mm Hg, pulse is 88/min, and respirations are 16/min.  Physical examination demonstrates an awake but tired-appearing adolescent.  There is no rhinorrhea, tympanic membranes are clear, and tonsils are enlarged and erythematous with white exudate bilaterally.  There is tender cervical lymphadenopathy but no neck stiffness.  S1 and S2 are normal.  Lungs are clear to auscultation bilaterally.  The abdomen is soft and nontender with mild hepatosplenomegaly.  A diffuse, erythematous, blanching, maculopapular rash is seen on the chest, abdomen, and extremities.  Laboratory results are as follows:

Item 1 of 2

In addition to discontinuing antibiotics, which of the following is the most appropriate management for this patient’s rash?

Item 2 of 2

An appropriate diagnosis is made and the correct management is initiated.  Which of the following is a true statement about the patient’s condition?

An 18-month-old boy is brought to the office for right ear pain.  About 4 weeks ago, he had fever and right ear pain and was prescribed a 10-day course of high-dose amoxicillin for acute otitis media; he completed the course and had a normal follow-up visit 2 weeks ago.  While on the medication, he experienced improvement in his symptoms.  For the past 3 days, he has been tugging on his right ear and crying; he developed fever today.  He has no nasal congestion, neck stiffness, cough, emesis, or other symptoms.  He is otherwise healthy and takes no medications.  His immunizations are up to date.  Temperature is 38.5 C (101.3 F), blood pressure is 108/66 mm Hg, pulse is 96/min, and respirations are 21/min.  Physical examination demonstrates an alert, uncomfortable child.  Pupils are equal and reactive; the conjunctivae are injected bilaterally and have purulent discharge.  There is no rhinorrhea or sinus tenderness.  The external ears appear normal and are not painful to manipulation; there is no drainage in the external canal.  The right tympanic membrane is erythematous, bulging, and immobile on pneumatic air insufflation.  The left tympanic membrane appears normal.  Both mastoids are nontender and nonerythematous.  The neck is nontender and has full range of motion.  Cardiopulmonary examination is normal.

Item 1 of 2

Which of the following is the most likely cause of this patient’s current symptoms?

Item 2 of 2

An appropriate diagnosis is made, and the treatment options are discussed with the patient’s mother.  What is the most appropriate next step in management of this boy’s condition?

A 10-year-old girl is brought to the emergency department for evaluation of a bite wound.  Last night, the girl had a fight with her 12-year-old stepbrother, who bit her on the forearm.  This morning, the girl’s arm “looks worse.”  The stepbrother is HIV-positive and acquired it from his mother at birth.  He takes antiretroviral therapy; his most recent CD4 count was 1100 cells/µL, and his HIV viral load was undetectable.  The patient has no known medical problems, and takes no medications.  Her vital signs are normal.  Examination shows 2 deep puncture wounds on the left forearm.  There is warmth, erythema, and swelling around the bite marks.  The skin is mildly tender to palpation.  No fluctuance is palpated.

Item 1 of 2

The patient is at greatest risk for developing an infection from which of the following organisms?

Item 2 of 2

The wound is irrigated thoroughly with saline and local wound care is provided.  Which of the following is the most appropriate next step in management of this patient?

A 3-year-old girl is brought to the emergency department due to pain and fever.  Two days ago, the patient developed mild abdominal and back pain.  The fever began yesterday morning and reached 40.1 C (104.2 F) last night.  Over the past 8 hours, she had 6 episodes of emesis but has since tolerated a few sips of water.  The patient has a history of constipation since the start of toilet training at age 2 and has pellet-like stools once a week.  She has frequent urinary accidents during the day and night.  The patient takes no medications and has no other medical conditions.  Vaccinations are up to date.  Temperature is 40 C (104 F), blood pressure is 95/70 mm Hg, pulse is 110/min, and respirations are 20/min.  Physical examination shows a tired-appearing girl with dry mucous membranes.  She has right costovertebral tenderness.  The abdomen is soft, nontender, and nondistended.  The remainder of the examination is unremarkable.  Laboratory results are as follows:

Blood and urine culture results are pending.  A 20-mL/kg normal saline bolus is administered.  The patient has another episode of emesis and an additional void in the emergency department.

Item 1 of 2

Which of the following is the best next step in management of this patient?

Item 2 of 2

The patient is admitted to the hospital, and intravenous ceftriaxone is started.  Urine culture is positive for Escherichia coli that is sensitive to third-generation cephalosporins.  Blood culture is negative.  After 48 hours, the patient is tolerating oral fluids and is afebrile.  She is discharged from the hospital on oral cefdinir.  Which of the following should be recommended to reduce the risk for infection recurrence in this patient?

A 6-year-old girl is brought to a walk-in clinic for evaluation of growth.  The patient and her family immigrated to the United States from Haiti 2 months ago.  For the past 3 months, decreased appetite has led to the loss of several pounds.  The patient has had occasional episodes of abdominal discomfort and diarrhea.  The family denies any recent changes to her diet.  There is no gross blood or mucus in the stool, and the patient has no fever.  A mild cough early in the course of symptoms has since resolved.  The patient received all age-appropriate vaccinations prior to immigration.  She was also immunized in infancy for bacille Calmette-Guérin.  Skin tuberculin testing at the time of immigration showed 2 mm induration.  Temperature is 36.7 C (98.1 F), pulse is 102/min, and respirations are 18/min.  Height is 120 cm (4 ft, 10th percentile) and weight is 19 kg (41.9 lb, <5th percentile).  Physical examination shows a slightly distended abdomen with soft, hyperactive bowel sounds.  There is generalized mild tenderness to deep palpation.  No guarding, rebound tenderness, or hepatosplenomegaly is present.  Fecal occult blood test is positive.  Laboratory results are as follows:

Which of the following diagnostic studies is most likely to be abnormal in this patient?

A 15-year-old boy is brought to the office due to fever.  He has had fever, chills, fatigue, and myalgias for the past 10 days.  He has lost some weight, which was attributed to poor appetite.  Three weeks ago, the patient and his family returned from a trip to the Dominican Republic; he has not traveled anywhere else.  There are no sick contacts at home.  The patient has no significant medical history and takes no medications.  Temperature is 38.3 C (101 F), blood pressure is 110/60 mm Hg, and pulse is 108/min.  Physical examination shows a tired-looking boy in no acute distress.  The tympanic membranes are not erythematous; mucous membranes are moist; and tonsils are enlarged and erythematous with white exudate.  S1 and S2 are normal without murmurs.  The lungs are clear to auscultation bilaterally.  Lymphadenopathy is present in the anterior cervical, posterior cervical, axillary, and inguinal chains.  The abdomen is soft and nontender.  Laboratory results are as follows:

The peripheral blood smear is shown in the image:

What is the most likely reason for these findings?

A 16-year-old boy is brought to the emergency department via ambulance.  The boy is accompanied by the school nurse, who notes that he has had a day of headache and generalized body aches that did not respond to acetaminophen.  He felt well enough to attend school and to work his part-time job at a local hardware store after school for 2 hours yesterday.  However, this morning his headache worsened and he was extremely drowsy.  The paramedics administered intravenous normal saline; no other interventions were required during transport.  As soon as he arrives in the emergency department, he becomes lethargic, has a seizure, and is immediately intubated by a resident physician.  Subsequent evaluation reveals that the patient has acute meningococcal meningitis.

Item 1 of 2

In addition to the patient’s family members, which of the following contacts requires antibiotic prophylaxis to prevent the development of meningococcal meningitis?

Item 2 of 2

The individuals requiring antibiotic prophylaxis are identified and contacted.  Which of the following is the most appropriate therapy for chemoprophylaxis against meningococcal meningitis?

A 3-year-old boy is brought to the emergency department due to 10 days of diarrhea.  The diarrhea started out watery but has become bloody over the past few days although he is stooling less frequently.  He has voided only twice in the past 24 hours.  Temperature is 38.3 C (101 F), blood pressure is 96/62 mmHg, heart rate is 145/min.  He is difficult to arouse and appears pale.  He is tachycardic with otherwise unremarkable heart and lung sounds.  His abdomen is soft, mildly distended, and tender to palpation in the left lower quadrant.  There are no rashes.  Initial laboratory studies show:

Numerous fragmented red blood cells are noted on blood smear.  Stool culture is pending, and PCR testing reveals Shigella dysenteriae type 1.  Which of the following is the most appropriate therapy in this patient?

An 8-year-old girl is brought to the physician for abnormal behavior.  She has been acting inappropriately, crying, and laughing without apparent reason for the past 2 weeks.  At school, she was restless and easily distracted.  Last week, her parents noted strange movements of the girl’s hands that improved when she slept.  On the day before presentation, her parents noticed rapid jerking movements of her face and feet.  The girl has had minor, self-resolving upper respiratory infections but has otherwise been healthy.  She takes no medications and her vaccinations are up-to-date.  Examination shows an alert and cooperative girl with normal vital signs.  Facial grimacing and tongue fasciculations are seen.  The lungs are clear to auscultation and a II/VI holosystolic murmur is heard at the apex.  When the girl speaks, distinct changes in the volume and pitch of her voice are noted.  Muscular tone is mildly decreased globally.  Pronator sign is positive, and the relaxation phase of the patellar reflex is delayed.

Item 1 of 2

Which of the following is the most likely diagnosis?

Item 2 of 2

The child’s diagnosis is discussed with her parents, who would like to know more about treatment of the condition.  Which of the following is the most appropriate medication for this patient?